/*
 * Copyright (C) 2014 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.graph;

import com.google.common.annotations.Beta;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CompatibleWith;

/**
 * A subinterface of {@link Graph} which adds mutation methods. When mutation is not required, users
 * should prefer the {@link Graph} interface.
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @param <N> Node parameter type
 * @since 20.0
 */
@Beta
public interface MutableGraph<N> extends Graph<N> {

    /**
     * Adds {@code node} if it is not already present.
     *
     * <p>
     * <b>Nodes must be unique</b>, just as {@code Map} keys must be. They must also be non-null.
     *
     * @return {@code true} if the graph was modified as a result of this call
     */
    @CanIgnoreReturnValue
    boolean addNode(N node);

    /**
     * Adds an edge connecting {@code nodeU} to {@code nodeV} if one is not already present. In an
     * undirected graph, the edge will also connect {@code nodeV} to {@code nodeU}.
     *
     * <p>
     * Behavior if {@code nodeU} and {@code nodeV} are not already present in this graph is
     * implementation-dependent. Suggested behaviors include (a) silently {@link #addNode(Object)
     * adding} {@code nodeU} and {@code nodeV} to the graph (this is the behavior of the default
     * implementations) or (b) throwing {@code IllegalArgumentException}.
     *
     * @return {@code true} if the graph was modified as a result of this call
     * @throws IllegalArgumentException if the introduction of the edge would violate
     *         {@link #allowsSelfLoops()}
     */
    @CanIgnoreReturnValue
    boolean putEdge(N nodeU, N nodeV);

    /**
     * Removes {@code node} if it is present; all edges incident to {@code node} will also be
     * removed.
     *
     * @return {@code true} if the graph was modified as a result of this call
     */
    @CanIgnoreReturnValue
    boolean removeNode(@CompatibleWith("N") Object node);

    /**
     * Removes the edge connecting {@code nodeU} to {@code nodeV}, if it is present.
     *
     * @return {@code true} if the graph was modified as a result of this call
     */
    @CanIgnoreReturnValue
    boolean removeEdge(@CompatibleWith("N") Object nodeU, @CompatibleWith("N") Object nodeV);
}
